Mystery in the Sand: The Alden family is spending sunny days at the shore and summer nights in the mobile home right on the beach! One morning Benny finds a gold necklace in the sand, and a search for its owner begins a trail of clues that leads to Tower House, the strange old mansion nearby. What will the Boxcar Children find there? Mystery Behind the Wall: The Aldens have found a mystery under their very own roof! When the children found an old journal behind the closet wall in the guest room, they never dreamed it would lead them on a search for valuable coins. What happened to the girl who wrote the journal -- and what is she trying to tell them? Bus Station Mystery: The Aldens are bound for the Science and Hobby Fair, but when a bad storm hits, they're forced to stay in the bus station. Before they know it, the Boxcar Children are in the middle of a mystery involving a polluted river, two strange boys, and a bus station manager who knows more than anyone suspects....